Comparison of imaging findings of surgical necrotizing enterocolitis between extremely preterm and preterm infants

Advances in neonatal care have improved survival of extremely premature infants (<28 weeks gestational age (GA)), especially with necrotizing enterocolitis (NEC).

To evaluate if imaging features of NEC differ between extreme premature and premature infants.

We retrospectively reviewed the abdominal radiograph and/or ultrasound obtained immediately prior to surgically proven diagnosis of NEC in our neonatal intensive care unit infants January 2020-January 2025. Two blinded pediatric radiologists reviewed imaging, and a third acted as a tie-breaker in case of discordant review. Patients were stratified by GA (<28 weeks vs. ≥28 weeks) and birth weight (<1,500 g vs. ≥1,500 g). Chi-square test was used to assess differences in imaging findings.

Ninety patients met inclusion criteria (median age 21.5 days); 43.3% (n=39) female. In total, 56% (50/90) had GA <28 weeks and 86% (77/90) had birth weight <1,500 g. All 90 patients had abdominal radiographs; only 19% (17/90) had bowel ultrasound. In unadjusted analyses, we found that infants with GA <28 weeks were more likely to demonstrate paucity of bowel gas (OR 4.64, 95%CI 1.41-15.2, P-value 0.01), and less likely to have fixed bowel loops (OR 0.16, 95%CI 0.04-0.62, P-value 0.01) or pneumatosis intestinalis (OR 0.38, 95%CI 0.15-0.96, P-value 0.04). After adjusting for birth weight, those with GA <28 weeks were less likely to show pneumatosis intestinalis on radiographs (OR 0.31 (95%CI 0.11, 0.87), P-value 0.03) as compared to infants ≥28 weeks GA. For ultrasound findings, no imaging features were significantly different based on stratification based on gestation age or birth weight (all P>0.05).

Extremely premature (<28 weeks) and very low birth weight (<1,500 g) infants tend to show fewer classic radiographic signs of NEC, i.e., pneumatosis intestinalis and fixed bowel loops, and more often exhibit a paucity of bowel gas.